1. Field of the Invention
The present invention concerns a toner manufacturing method, a toner manufacturing apparatus, and a toner.
2. Related Art
Various methods are known for performing electrophotography, and they generally include a step of forming electric latent images on a light sensitive body by various mechanisms while utilizing photoconductive material (an exposure step), a developing step of developing the latent images by using a toner (a fine resin particle), a transfer step of transferring toner images onto a transfer material such as paper and a step of fixing the toner images by heating, pressing, or the like using a fixing roller.
As the method of manufacturing the toner used in electrophotography, a pulverization method and a polymerization method are typically used.
The pulverization method is a method of kneading a material containing a resin as a main ingredient (hereinafter simply referred to also as a “resin”) and a colorant at a temperature higher than the softening point of the resin to obtain a kneaded product and then cooling and pulverizing the kneaded product. The pulverization method is excellent in that the material can be selected from a wide range and a toner can be manufactured relatively easily. However, the toner obtained by the pulverization method has a drawback in that the shape varies greatly between each of the particles and the grain size distribution thereof tends to be broad. As a result, the charging property, the fixing property, and the like vary greatly between each of the toner particles which lowers the reliability for the entire toner.
The polymerization method manufactures toner particles by using a monomer as a constituent ingredient for the resin, and conducting a polymerizing reaction, for example, in a liquid phase thereby forming an aimed resin. In the polymerization method, the polymerizing reaction is usually conducted in a liquid phase containing a dispersant with the aim of improving the dispersibility of a dispersoid (dispersoid to form toner particles), obtaining mono-dispersion, controlling the molecular weight distribution, and the like. The polymerization method is excellent in that the obtained toner particle can be made to a shape of a relatively high sphericalness (a shape approximate to a geometrical complete spherical shape). However, in the existent polymerization method, it is difficult to obtain a toner having an excellent charging property in the finally obtained toner. That is, the existent polymerization method has a problem in that it is difficult to obtain a sufficiently large absolute value for the charged amount of the toner particle and the charging property (charged amount) between each of the toner particles tends to vary greatly in the finally obtained toner.
In recent years a method of manufacturing toner particles by discharging a liquid dispersion containing a material for manufacturing a toner using a so-called ink jet method (for example, refer to JP-A No. 2004-70303) has been proposed. In the method described above, a liquid dispersion with the addition of a dispersant is used with an aim of making the content of the dispersoid uniform in the discharged liquid droplet or enabling the liquid dispersion to be discharged. That is, in a case of using a liquid dispersion not containing the dispersant, a toner of uniform shape and size can not be obtained and, further, discharge of the liquid dispersion is impossible. In a case of adopting such an ink jet method, while variation of the shape and the size between each of the particles can be relatively decreased, it is also difficult to obtain a toner having an excellent charging property like in the polymerization method described above.
As described above, in a case of adopting a method of using the liquid dispersion, while variation of the shape between each of the particles (toner particles) can be decreased, it is difficult to obtain a toner having an excellent charging property. In addition, in a case of adopting the method of using the liquid dispersion, the obtained toner is poor in circumstantial properties (e.g., water proofness and storability) and caused agglomeration between the toner particles when stored in a cartridge (particularly, stored at a high humidity condition), which results in undissolved clumps (so-called DAMA).
The present inventors have made an earnest study with an aim of solving such problems. As a result, the present inventors have found that the dispersant contained in the liquid dispersion gives undesired effects on the charging property of the toner when it remains in the toner and, further, have found that the dispersant can be selectively removed by the combined use of ozone and UV-rays and, as a result, a toner having an excellent property can be obtained.